Method of reducing corrosion potential and stress corrosion cracking susceptibility in nickel-base alloys

ABSTRACT

A method for reducing in situ the electrochemical corrosion potential and susceptibility to stress corrosion cracking of a nickel-base alloy and boiling water nuclear reactor components formed therefrom when in contact with high temperature water. The method comprises the steps of: adding a metal hydride to the high temperature water; dissociating the metal hydride in the high temperature water to form a metal and at least one hydrogen ion; and reducing the concentration of the oxidizing species by reacting the hydrogen ions with an oxidizing species, thereby reducing in situ the electrochemical corrosion potential of the nickel-base alloy. The method may further include the steps of reacting the metal with oxygen present in the high temperature water to form an insoluble oxide and incorporating the metal into the surface of the nickel-base alloy, thereby reducing the electrical conductivity of the surface of the nickel-base alloy. A nickel-base alloy component having a reduced electrochemical corrosion potential is also disclosed.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to protecting nickel-base alloysand components thereof from stress corrosion cracking when in contactwith high temperature water. More particularly, the invention relates toprotecting nickel-base alloy components of a boiling water reactor (BWR)from stress corrosion cracking when in contact with high temperaturewater. Even more particularly, the invention relates to protectingnickel-base alloy components of a boiling water reactor (BWR) fromstress corrosion cracking when in contact with high temperature water bylowering the electrochemical corrosion potential of the nickel-basealloy components.

[0002] Nickel-base alloys, such as alloys 600, 690, 182, 82, X750, 718,and superalloys, have found applications in both boiling water nuclearreactors (hereinafter referred to as BWRs) and pressurized water nuclearreactors (hereinafter referred to as PWRs). These applications includeuse in many structural components found in nuclear reactors, such as,but not limited to, pipes, bolts, and weld material. Water for coolingthe reactor core and extracting heat energy therefrom circulates withinthe BWR reactor pressure vessel, with about 15% of the water charged tosteam. Inside the BWR reactor pressure vessel, the steam and circulatingwater typically have an operating pressure and temperature of about 7MPa and 288° C., respectively. For a PWR, the circulating water has anoperating pressure of about 15 MPa and a temperature of about 320° C. Inthe presence of water and/or steam under such high pressures andtemperatures, components formed from nickel-base alloys are subject tointergranular stress corrosion cracking (hereinafter referred to asIGSCC), more commonly, or generically, referred to stress corrosioncracking (hereinafter referred to as SCC).

[0003] Stress corrosion cracking (SCC) of nuclear reactor components haslong been a concern. As used herein, SCC refers to cracking propagatedby the application of static or dynamic tensile stresses in combinationwith corrosion at a crack tip. The stresses encountered within BWR andPWR pressure vessels include those arising from the operating pressurefor containment of the high temperature water in a liquid state,vibration, differences in thermal expansion, residual stress fromwelding, and fabrication-related sources of stress. Various materialsand environmental conditions, such as water chemistry, welding, surfacenature, crevice geometry, heat treatment, radiation, and other factorscan also increase the susceptibility of reactor components to SCC.

[0004] Boiling water reactors use water as a means of cooling nuclearreactor cores and extracting heat energy produced by such reactor cores.Stress corrosion cracking is of particular concern in BWRs, asradiolytic decomposition of the high temperature water in the BWR coreincreases the concentrations of oxidizing agents, such as O₂ and H₂O₂,in the high temperature water that circulates through the reactor.Consequently, the likelihood of extensive SCC in materials that areexposed to the high temperature reactor water is substantiallyincreased. SCC can eventually lead to the failure of a nickel-base alloystructural component, such as a bolt. The premature failure of suchcomponents may lead to repeated or early shutdown of the reactor forpart replacement or repair, thus reducing the amount of time the reactoris available for power generation.

[0005] The electrochemical corrosion potential (hereinafter referred toas ECP) affects the susceptibility of BWR components to SCC. The ECP isthe mixed potential associated with the equilibrium of redox reactionsoccurring on a metal surface and the metal dissolution, and is dependentupon the amounts of oxidizing and reducing species present in thereactor water. In BWR reactor water, cathodic currents associated withthe reduction of oxygen and hydrogen peroxide are balanced by anodiccurrents involving hydrogen oxidation and corrosion of metalliccomponents.

[0006] Several approaches have been adopted to reduce SCC by loweringthe ECP of the reactor water. In one such method, commonly referred toas hydrogen water chemistry (HWC), gaseous hydrogen is added to the BWRfeedwater. Hydrogen addition reduces the oxidant concentrations, andthus reduces SCC susceptibility, by recombining with dissolved oxidantsthat are produced by the radiolysis of water in the reactor core. Onedisadvantage of HWC is that large amounts of hydrogen are needed tosufficiently lower the concentration of dissolved oxygen and to achievea low corrosion potential. In addition, HWC can also increase radiationlevels in the reactor steam by increasing the volatility of radioactiveN¹⁶.

[0007] A second approach, known as noble metal technology (NMT), reducesthe susceptibility of BWR components to stress corrosion cracking bylowering the corrosion potential more efficiently; i.e., by reducing theamount of hydrogen required to lower the electrochemical corrosionpotential. The objective of NMT is to improve the catalytic propertiesfor hydrogen/oxygen recombination on metal surfaces. Niederach (U.S.Pat. No. 5,130,080), Andresen and Niederach (U.S. Pat. Nos. 5,135,709and 5,147,602), and Hettiarachchi (U.S. Pat. No. 5,818,893) havedisclosed various NMT application methods, such as the thermal sprayingof noble metal and noble metal alloy coatings on reactor components andnoble metal chemical addition on metal reactor components. The NMTprocess lowers the corrosion potential to below −500 mV_(SHE) (standardhydrogen electrode) with a small amount of hydrogen addition. Whencombined with hydrogen addition in stoichiometric proportions orgreater, complete recombination of oxygen and hydrogen peroxide on thecatalytic surface of the noble metal is achieved and the corrosionpotential is dramatically reduced.

[0008] Other methods, which do not require the addition of hydrogen toreduce the corrosion potential of reactor components—particularly ofsteel vessels and piping have been developed. Because electricallyinsulating films on metal surfaces reduce the corrosion potential, theECP is also affected by the electrical conductivity of oxide filmsformed on metals in high temperature water. By lowering theelectrochemical corrosion potential of metal components, thesusceptibility of such materials to SCC can be significantly reduced.Andresen and Kim (U.S. Pat. No. 5,465,281) and Hettiarachchi (U.S. Pat.No. 5,774,516) teach a method of reducing the electrochemical corrosionpotential of steel exposed to high temperature water with an insolubleand electrically non-conductive material, such as zirconia (ZrO₂),alumina (Al₂O₃), or yttria-stabilized zirconia (YSZ) powders. However,air plasma spray coatings generally must be applied to the componentseither prior to installation or during a power outage. Moreover, it isdifficult to achieve complete coverage with injection of insolublechemical compounds into the reactor water.

[0009] More recently, Andresen and Kim (U.S. Pat. No. 6,024,805) havedisclosed an in situ method of reducing the ECP and thus lowering thesusceptibility of stainless steel that is exposed to high temperaturewater to stress corrosion cracking. The method includes the addition ofa metal hydride to the high temperature water.

[0010] The prior art has focused on reducing in situ the corrosionpotential of stainless steel pressure vessels and piping within BWRs.While insulating oxide coatings have been applied to nickel-base alloys,to date no attempt has been made to reduce in situ the susceptibility ofnickel-base alloys to stress corrosion cracking by lowering theelectrochemical potential of the alloy in the BWR without addinghydrogen to the reactor water. Therefore, what is needed is a method oflowering the susceptibility of nickel-base alloys that are exposed tohigh temperature water to SCC. What is also needed is a method oflowering the ECP of nickel-base alloys exposed to high temperaturewater, thereby mitigating stress corrosion cracking in such alloys.Finally, what is also needed is a nickel-based alloy having a reducedcorrosion potential, and thus, a reduced susceptibility to stresscorrosion cracking.

BRIEF SUMMARY OF THE INVENTION

[0011] The present invention meets these needs and others by providing amethod of reducing in situ the ECP of a nickel-base alloy that is incontact with high temperature water, such as in, but not limited to, thepressure vessel of a BWR, without adding hydrogen to the water. Thepresent invention also provides an article formed from a nickel-basealloy having a reduced corrosion potential.

[0012] Accordingly, one aspect of the present invention is to provide amethod for reducing in situ an electrochemical corrosion potential of anickel-base alloy having a surface that is in contact with hightemperature water, the electrochemical corrosion potential beingproportional to the concentration of oxidizing species present in thehigh temperature water. The method comprises the steps of: adding ametal hydride to the high temperature water, the metal hydride beingcapable of dissociating in water; dissociating the metal hydride in thehigh temperature water to provide a metal and hydrogen ions; andreducing the concentration of the oxidizing species by reacting thehydrogen ions with the oxidizing species, thereby reducing in situ theelectrochemical corrosion potential of the nickel-base alloy.

[0013] A second aspect of the present invention is to provide a methodof reducing the in situ susceptibility of a nickel-base alloy componentthat is in contact with high temperature water in a boiling waternuclear reactor to stress corrosion cracking. The method comprises thesteps of: adding a metal hydride to the high temperature water, themetal hydride being capable of dissociating in water; dissociating themetal hydride in the high temperature water to provide a metal andhydrogen ions; and incorporating the metal into an oxide layer disposedon a surface of the nickel-base alloy, the oxide layer being in contactwith the high temperature water, wherein the electrical conductivity ofthe surface of the nickel-base alloy is reduced, and wherein theresulting decrease in the electrical conductivity reduces in situ thesusceptibility of stress corrosion cracking of the nickel-base alloycomponent.

[0014] A third aspect of the present invention is to provide a method ofreducing in situ susceptibility of stress corrosion cracking of anickel-base alloy component that is in contact with high temperaturewater in a boiling water nuclear reactor, the susceptibility of stresscorrosion cracking being proportional to the concentration of oxidizingspecies present in the high temperature water. The method comprises thesteps of: adding a metal hydride to the high temperature water, themetal hydride being capable of dissociating in water; dissociating themetal hydride in the high temperature water to provide a metal andhydrogen ions; reducing the concentration of the oxidizing species, theoxidizing species being selected from the group consisting of O₂ andH₂O₂, by reacting the hydrogen ions with the oxidizing species, therebyreducing in situ the electrochemical corrosion potential of thenickel-base alloy; and incorporating the metal into an oxide layerdisposed on a surface of the nickel-base alloy, the oxide layer being incontact with the high temperature water, wherein the electricalconductivity of the surface of the nickel-base alloy is reduced, andwherein the resulting decrease in the electrical conductivity reduces insitu the susceptibility of stress corrosion cracking of the nickel-basealloy component.

[0015] Finally, a fourth aspect of the present invention is to provide anickel-base alloy component having a reduced susceptibility to stresscorrosion cracking when said nickel-base alloy component is in contactwith high temperature water. The nickel-base alloy component comprises:a nickel-base alloy; a surface and a layer disposed thereon, the layerbeing formed from an oxide of a first metal and being in contact withthe high temperature water; and at least a second metal incorporated inthe layer, wherein the second metal is incorporated in situ into thelayer by adding a hydride of the second metal to the high temperaturewater, dissociating the hydride in the high temperature water, andincorporating the second metal into said oxide of said first metal.

[0016] These and other aspects, advantages, and salient features of theinvention will become apparent from the following detailed description,the accompanying figures, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a plot of the electrochemical corrosion potential (ECP)of 304 stainless steel and nickel-base alloy 690 as a function of oxygenconcentration in 288° C. water with the addition of zirconium hydrideand without the addition of zirconium hydride; and

[0018]FIG. 2 is a plot of the effect of the addition of zirconiumhydride (ZrH₂) on hydrogen and oxygen concentrations in 288° C. water.

DETAILED DESCRIPTION OF THE INVENTION

[0019] In the following description, like reference characters designatelike or corresponding parts throughout the several views shown in thefigures. It is also understood that terms such as “top,” “bottom,”“outward,” “inward,” and the like are words of convenience and are notto be construed as limiting terms.

[0020] Referring to the figures and examples in general, it will beunderstood that the illustrations are for the purpose of describing apreferred embodiment of the invention and are not intended to limit theinvention thereto.

[0021] The present invention discloses a new approach for achieving lowcorrosion potentials on nickel base alloys, such as alloys 600, 690,182, 82, 718, X750, weld metals, nickel-base superalloys, and the like,that are widely used in BWRs. Unlike other methods found in the priorart for reducing the electrochemical corrosion potential (ECP) ofmaterials used in BWRs, the method of the present invention does notrequire that hydrogen be separately added. In the present invention, ametal hydride MH_(n) is injected into the reactor feedwater. The metalhydride can be directly injected as either a powder or slurry, or bysuspending a metal hydride powder into the feedwater.

[0022] Once introduced into the reactor feedwater, the metal hydrideMH_(n) dissociates in high temperature water to yield the elementalmetal and at least one hydrogen ion H⁺, as represented by the generalreaction

MH_(n)→M+nH⁺+ne⁻  (1).

[0023] The high radiation flux within the BWR pressure vessel enhancesthe rate of dissociation of the metal hydride compound. In the presentinvention, the metal hydride that is used to lower the ECP of thenickel-base alloy is a hydride of a metal selected from the groupconsisting of hafnium, lanthanum, lithium, manganese, molybdenum,sodium, niobium, neodymium, palladium, praseodymium, plutonium,samarium, strontium, tantalum, thorium, titanium, uranium, vanadium,yttrium, and zirconium.

[0024] The concentrations of oxidizing species, such as O₂ or H₂O₂ , inthe high temperature water are reduced as the oxidizing species reactwith the hydrogen ions released by the dissociation of the metal hydrideMH_(n), thus lowering the ECP of Ni-based alloy components in the BWR.Oxygen, for example, reacts with the hydrogen ions released by thehydride decomposition, to yield water according to the reaction

4e⁻+4H⁺+O₂→2H₂O  (2).

[0025] By reducing the concentrations of such oxidizing species, thecorrosion potential and susceptibility of the nickel-base alloys thatare exposed to the high temperature reactor water to stress corrosioncracking is correspondingly lowered.

[0026] In addition to reducing the ECP by providing hydrogen ions thatreact with oxidizing species present in the high temperature water, thepresent invention further reduces the ECP by incorporating the metalreleased by the decomposition of the metal hydride into the thin oxidelayer that is present on the surface of the nickel-base alloy.

[0027] The neutral metal atom that is produced by the metal hydridedissociation of equation 1 may be readily ionized according to thereaction

M→M^(n+)+ne⁻  (3).

[0028] The metal ion M^(n+)may then react with O²⁻ ions in the hightemperature water to form an oxide:

M^(n+)+O²⁻→MO(s)  (4),

[0029] which is then deposited on the thin oxide layer that is presenton the surface of the nickel-base alloy component. Alternatively, themetal ion M^(n+) may be incorporated into the thin oxide layer byreacting with a substance—typically, oxygen or an oxide—located in theoxide layer. The incorporation of the metal into the oxide layerdecreases the electronic conductivity of the oxide film and eventuallydecreases the ECP of the nickel-base alloy components, thus decreasingthe susceptibility of these components to stress corrosion cracking.Incorporation of the metal into the thin oxide layer on the nickel-basealloy surface typically occurs when hydrides of the metals found ingroups IIIB, IVB, and IVB of the periodic table are injected into thereactor feedwater. Preferably, zirconium hydride (ZrH₂), titaniumhydride (TiH₂), scandium hydride, hafnium hydride, niobium hydride, andvanadium hydride (VH₂) are the metal hydrides used for the incorporationthe metal into the thin oxide layer.

[0030] The present invention offers the advantage providing hydrogenions to reduce the concentration of oxidizing species within the reactorwater and reduce the corrosion potential of the nickel-base alloyreactor components while either reducing or eliminating the need to addgaseous hydrogen. Metal hydride injection results in a more evendistribution of hydrogen than that obtained when hydrogen gas is added,thereby providing a greater overall reduction of oxidizing agents, suchas O₂ or H₂O₂, in the water.

[0031] Moreover, the present invention further reduces the corrosionpotential and susceptibility of nickel-base alloy reactor components toSCC by uniformly incorporating metals in situ into the oxide layer thatis present on the surface of the nickel-base alloy. Air plasma sprayingof noble metals and oxide coatings are generally unable to be applied insitu during plant operation.

[0032] The following example serves to illustrate the features andadvantages of the present invention.

EXAMPLE 1

[0033] Electrochemical corrosion potential (ECP) measurements wereperformed on test electrodes of nickel-base alloy 690, 304 stainlesssteel, and zircaloy-2. The test electrodes were first pre-oxidized for 2weeks in 288° C. water containing 200 ppb oxygen prior to the ECPmeasurement. The ECP of each test electrode was then measured for 2 daysin 288° C. water containing 300 ppb oxygen. Suspensions of ZrH₂ werethen injected into the recirculating water loop, and argon gas waspurged through this injection solution during experiments. Oxygen andhydrogen concentrations in the outlet water were measured simultaneouslywith the ECP measurement.

[0034]FIG. 1 is plot of the electrochemical corrosion potential (ECP) of304 stainless steel and nickel-base alloy 690 as a function of oxygenconcentration in 288° C. water. As can be seen from FIG. 1, the additionof ZrH₂ decreased the ECP of the nickel-base alloy 690. No change inECP, however, was observed on the zircaloy 2 specimen, which had alreadyformed the insulating oxide (ZrO₂) on the surface. FIG. 2 shows theeffect of ZrH₂ addition on the oxygen and hydrogen concentrations in theoutlet water measured simultaneously with the ECP measurement. The ECPfor 304 SS was measured as a reference.

[0035] As seen in FIG. 1, the ECP of nickel-base alloy 690 decreases toabout −200 mVSHE with the addition of ZrH₂. The concentration ofhydrogen produced by the decomposition of ZrH₂ in the high temperaturewater increases with increasing ZrH₂ injection time, as seen in FIG. 2.The results shown in FIGS. 1 and 2 show that ZrH₂ addition providesvarious beneficial effects on nickel-base alloys that are in contactwith high temperature water. First, the hydrogen ions provided to thehigh temperature water by decomposing the metal hydride reduce theoxidant concentrations. Second, the metal from the metal hydride reactsin the high temperature water to form insoluble metal oxides which arethen incorporated into the thin oxide layers that are present on thesurface of nickel-base alloy components, thereby decreasing the electricconductivity of the component. These processes decrease the ECP ofnickel-base alloys that are exposed to the high temperature water,thereby reducing the susceptibility of the alloys to SCC in hightemperature water.

[0036] While various embodiments are described herein, it will beappreciated from the specification that various combinations ofelements, variations or improvements therein may be made by thoseskilled in the art, and are within the scope of the invention. Forexample, the methods of the present invention are applicable to a widerange of water chemistry environments where a low corrosion potentialleads to reduced SCC susceptibility.

What is claimed is:
 1. A method for reducing in situ an electrochemicalcorrosion potential of a nickel-base alloy having a surface that is incontact with high temperature water, the electrochemical corrosionpotential being proportional to the concentration of oxidizing speciespresent in the high temperature water, the method comprising the stepsof: a) adding a metal hydride to the high temperature water, the metalhydride being capable of dissociating in water; b) dissociating themetal hydride in the high temperature water to provide a metal andhydrogen ions; and c) reducing the concentration of the oxidizingspecies by reacting the hydrogen ions with the oxidizing species,thereby reducing in situ the electrochemical corrosion potential of thenickel-base alloy.
 2. The method of claim 1, further including the stepof incorporating the metal into the surface of the nickel-base alloy,thereby reducing the electrical conductivity of the surface of thenickel-base alloy.
 3. The method of claim 2, wherein the metal hydrideis a hydride of a metal selected from the group consisting of Group IIIBmetals, Group IVB metals, and Group VB metals.
 4. The method of claim 3,wherein the metal hydride is a metal hydride selected from the groupconsisting of zirconium hydride, titanium hydride, vanadium hydride,hafnium hydride, scandium hydride, niobium hydride, and combinationsthereof.
 5. The method of claim 2, wherein the surface of thenickel-base alloy includes an oxide film disposed thereon, and whereinthe step of incorporating the metal into the surface of the nickel-basealloy comprises incorporating the metal into the oxide film.
 6. Themethod of claim 1, wherein the metal hydride is a hydride selected fromthe group consisting of hafnium hydride, lanthanum hydride, lithiumhydride, manganese hydride, molybdenum hydride, sodium hydride, niobiumhydride, neodymium hydride, palladium hydride, praseodymium hydride,plutonium hydride, samarium hydride, strontium hydride, tantalumhydride, titanium hydride, thorium hydride, uranium hydride, vanadiumhydride, yttrium hydride, and zirconium hydride.
 7. The method of claim1, wherein the step of adding a metal hydride to the high temperaturewater comprises injecting a metal hydride solid into the hightemperature water.
 8. The method of claim 1, wherein the nickel-basealloy is a nickel-base alloy selected from the group consisting of alloy600, alloy 690, alloy 182, alloy 82, alloy 718, alloy X750, weld metals,and nickel-base superalloys.
 9. The method of claim 1, wherein theoxidizing species is at least one species selected from the groupconsisting of oxygen and hydrogen peroxide.
 10. A method of reducing thein situ susceptibility of a nickel-base alloy component that is incontact with high temperature water in a boiling water nuclear reactorto stress corrosion cracking, the method comprising the steps of: a)adding a metal hydride to the high temperature water, the metal hydridebeing capable of dissociating in water; b) dissociating the metalhydride in the high temperature water to provide a metal and hydrogenions; and c) incorporating the metal into an oxide layer disposed on asurface of the nickel-base alloy, the oxide layer being in contact withthe high temperature water, wherein the electrical conductivity of thesurface of the nickel-base alloy is reduced, and wherein the resultingdecrease in the electrical conductivity reduces in situ thesusceptibility of stress corrosion cracking of the nickel-base alloycomponent.
 11. The method of claim 10, wherein the metal hydride is ahydride of a metal selected from the group consisting of Group IIIBmetals, Group IVB metals, and Group VB metals.
 12. The method of claim10, wherein the metal hydride is a hydride selected from the groupconsisting of zirconium hydride, titanium hydride, vanadium hydride, andmixtures thereof.
 13. The method of claim 10, wherein the nickel-basealloy component comprises a nickel-base alloy selected from the groupconsisting alloy 600, alloy 690, alloy 182, alloy 82, alloy 718, alloyX750, weld metals, and nickel-base superalloys.
 14. A method of reducingin situ susceptibility of stress corrosion cracking of a nickel-basealloy component that is in contact with high temperature water in aboiling water nuclear reactor, the susceptibility of stress corrosioncracking being proportional to the concentration of oxidizing speciespresent in the high temperature water, the method comprising the stepsof: a) adding a metal hydride to the high temperature water, the metalhydride being capable of dissociating in water; b) dissociating themetal hydride in the high temperature water to provide a metal andhydrogen ions; c) reducing the concentration of the oxidizing species,the oxidizing species being selected from the group consisting of O₂ andH₂O₂, by reacting the hydrogen ions with the oxidizing species, therebyreducing in situ the electrochemical corrosion potential of thenickel-base alloy; and d) incorporating the metal into an oxide layerdisposed on a surface of the nickel-base alloy, the oxide layer being incontact with the high temperature water, wherein the electricalconductivity of the surface of the nickel-base alloy is reduced, andwherein the resulting decrease in the electrical conductivity reduces insitu the susceptibility of stress corrosion cracking of the nickel-basealloy component.
 15. The method of claim 14, wherein the metal hydrideis a hydride of a metal selected from the group consisting of Group IIIBmetals, Group IVB metals, and Group VB metals.
 16. The method of claim15, wherein the metal hydride is a hydride selected from the groupconsisting of zirconium hydride, titanium hydride, vanadium hydride, andmixtures thereof.
 17. The method of claim 14, wherein the nickel-basealloy component comprises a nickel-base alloy selected from the groupconsisting alloy 600, alloy 690, alloy 182, alloy 82, alloy 718, alloyX750, weld metals, and nickel-base superalloys.
 18. The method of claim1, wherein the step of adding a metal hydride to the high temperaturewater comprises injecting a metal hydride solid into the hightemperature water.
 19. A nickel-base alloy component having a reducedsusceptibility to stress corrosion cracking when said nickel-base alloycomponent is in contact with high temperature water, the nickel-basealloy component comprising: a) a nickel-base alloy; b) a surface and alayer disposed thereon, said layer being formed from an oxide of a firstmetal and being in contact with said high temperature water; and c) atleast a second metal incorporated in said layer, wherein said secondmetal is incorporated in situ into said layer by adding a hydride ofsaid second metal to the high temperature water, dissociating saidhydride in the high temperature water, and incorporating said secondmetal into said oxide of said first metal.
 20. The nickel-base alloycomponent of claim 19, wherein said hydride is a hydride of a metalselected from the group consisting of Group IIIB metals, Group IVBmetals, and Group VB metals.
 21. The nickel-base alloy component ofclaim 20, wherein said hydride is a hydride selected from the groupconsisting of zirconium hydride, titanium hydride, vanadium hydride, andmixtures thereof.
 22. The nickel-base alloy component of claim 19,wherein said nickel-base alloy is selected from the group consisting ofalloy 600, alloy 690, alloy 182, alloy 718, alloy X750, weld metals, andnickel-base superalloys.
 23. The nickel-base alloy component of claim19, wherein said nickel-base alloy component is a boiling water nuclearreactor component.